Generally, a “mesh” means a set of polygons used to describe the surfaces of a 3D object, and includes vertices indicating points used to determine the shape of a polygon which forms the mesh, edges indicating the lines of the polygon of the mesh, and faces indicating polygons which form the mesh.
Up to now, various post-treatment technologies have been researched and developed in order to improve the quality of a mesh. From among them, there is a method of removing aliasing effects from volume data generated at uniform grids and restoring sharp features.
For this purpose, a directed ‘distance field’ which is a developed type of a ‘distance field’ based on volume data is proposed. The ‘directed distance field’ uses vector data, including distance information to a curved surface in the respective directions of coordinate axes, instead of scalar data, including only distance information to a curved surface, so that some of the destruction of sharp features attributable to grid resolution can be prevented. The ‘directed distance field’ type volume data is transmitted to an extended marching cubes algorithm, and then used to finally restore apexes and edges.
In the extended marching cubes algorithm, a mesh is extracted from the directed distance field, one or more edges and apexes are determined by measuring the amount of variation of normals in the mesh, the determined edges and apexes are added as mesh vertices, and then a final mesh is generated using a diagonal swapping procedure. The last process of adding apexes and edges in the extended marching cubes algorithm may be a remeshing method applicable to a general mesh.
However, there is a problem in conventional method that it assumes that the shape of an original object and equation corresponding thereto have been already known, so that it is possible to expect the resolution of grids which make meaningful volume data to limit sharp features, such as edges, to a single grid cell. Therefore, feature points, such as edges and apexes, correspond to a single specific face of a mesh and are added in the form of mesh vertices, and the locations of original mesh vertices do not vary.
And, a particle system may be a simulation method generally used in computer graphics. An object is approximated by particles, and a governing equation is used in each of the particles, so that variation in and movement of the object are determined. Here, in the case in which the shape of the object, such as fluid or a deformable body, is not fixed, the surfaces of the object should be extracted using particles. Generally, each of the particles has an appropriate radius. If the surfaces of an object are extracted in consideration of the radii of respective particles, the vicinity of the edges or apexes of the object is round in shape. Therefore, although grid resolution increases, the portions of the edges of the object cannot be displayed with higher sharpness the radii of particlein the corresponding vicinity.
In this case, even though the conventional remeshing method is applied, results having little change are obtained. When the normal is changing smoothly, the conventional remeshing method is useless because the vicinity of edges is expressed to be round.